Vertical Storage Tanks Safety Assessment Methods Of Crack Defects In The Vault And The Shell-to-bottom Joint

With the development of industrial modernization, oil has become one of the most important consumer energy sources in the world. Vertical storage tank has a wide range of applications in the petrochemical industry. Vertical storage tanks are basic infrastructure in the development of oil and gas resources. Environmental pollution, fires, explosions and other serious secondary disasters often caused by the tank's damage.Once the tank is damaged, not only significant economic losses will be caused, but also people's life will be endangered. Therefore, safety assessment for the tank has become one of important researchs. At present, Safety assessment for in-service press vessels containing defects is used to identify tank's safety.Vertical storage tank is a pressure vessel and it is not fully applicable to Safety assessment for in-service press vessels containing defects. However, vertical storage tanks and pressure vessels have many similarities.For this reason, safety assessment methods in the Vault and the Shell-to-bottom Joint were studied by combining finite element analysis results with Safety assessment for in-service press vessels containing defects.Based on stress calculation theory in the vault and the shell-to-bottom joint and numerical simulation analysis method, vertical storage tanks safety assessment methods are investigated in this paper. The main research work as followings:(1) Importance of safety assessment of storage tank and its research development are provided. The main contents of this paper are put forward;(2) Stresses of storage tank in the the shell-to-bottom joint are tested by numerical analysis method. Finite element models of vertical storage tank without defect are established by using finite element software ADINA and most unfavorable position of crack defects is determined in the shell-to-bottom joint of vertical steel storage tank. Finite element stress analysis results in this position are compared with the results given by pressure vessel Stress solving method. Finally, topical solution of the stress calculation formula of the amendmentis which can be used for storage tank without defect is given;(3) According to stress calculation formula of the amendmentis and Safety assessment for in-service press vessels containing defects, stress in defect site is caculated. This stress is compared with stress which obtained from finite element analysis. The comparison results show that: finite element analysis solution is less than corrective solutions, both of the error is very small and corrective solutions are applicable to storage tank safety assessment in the shell-to-bottom joint. Finally, this paper provides a new method for steel storage tank safety assessment method which can be used in engineering practice in the shell-to-bottom joint;(4) Finite element models of vertical storage tank with crack-type defect in the vault are established. The most unfavorable position of the defects and stress of corrective solutions formula are given; this stress is compared with stress which obtained from finite element analysis. Finally, this paper provides a new method for steel storage tank safety assessment method which can be used in engineering practice in the vault. (5) Conclusions: the results of research in this paper are systematic summarized and the further research is put forward in this paper.